uterine (menstrual) cyclepchs.psd202.org/documents/dpohlman/1519742914.pdf · uterine (menstrual)...

PowerPoint® Lecture Slide Presentation

by Patty Bostwick-Taylor,

Florence-Darlington Technical College

PART C16

Reproductive

System

Uterine (Menstrual) Cycle

Cyclic changes of the endometrium

Regulated by cyclic production of estrogens and

progesterone

FSH and LH regulate the production of estrogens

and progesterone

Female cycles are about 28 days in length

Ovulation typically occurs about midway through

cycle on day 14

Stages of the menstrual cycle

Menstrual phase

Proliferative stage

Secretory stage

Menstrual phase

Days 1–5

Functional layer of the endometrium is

sloughed

Bleeding occurs for 3–5 days

By day 5, growing ovarian follicles are

producing more estrogen

Proliferative stage

Days 6–14

Regeneration of functional layer of the

endometrium

Estrogen levels rise

Ovulation occurs in the ovary at the end of

this stage

Secretory stage

Days 15–28

Levels of progesterone rise and increase the

blood supply to the endometrium

Endometrium increases in size and readies for

implantation

Secretory stage (continued)

If fertilization does occur

Embryo produces a hormone that causes

the corpus luteum to continue producing

its hormones

If fertilization does NOT occur

Corpus luteum degenerates as LH blood

levels decline

Fluctuation of Gonadotropin Levels

Figure 16.12a

Fluctuation of Ovarian Hormone Levels

Figure 16.12b

Ovarian Cycle

Figure 16.12c

Figure 16.12d

Hormone Production by the Ovaries

Estrogens

Produced by follicle cells

Cause secondary sex characteristics

Enlargement of accessory organs

Development of breasts

Appearance of axillary and pubic hair

Increase in fat beneath the skin, particularly in hips and breasts

Widening and lightening of the pelvis

Onset of menses (menstrual cycle)

Hormone Production by the Ovaries

Progesterone

Produced by the corpus luteum

Production continues until LH diminishes in

the blood

Does not contribute to the appearance of

secondary sex characteristics

Other major effects

Helps maintain pregnancy

Prepare the breasts for milk production

Developmental Stages of Ovarian Follicle

Figure 16.7

Mammary Glands

Present in both sexes, but only function in

females

Modified sweat glands

Function is to produce milk

Stimulated by sex hormones (mostly estrogens)

to increase in size

Anatomy of Mammary Glands

Areola—central pigmented area

Nipple—protruding central area of areola

Lobes—internal structures that radiate around

nipple

Lobules—located within each lobe and contain

clusters of alveolar glands

Alveolar glands—produce milk when a woman is

lactating (producing milk)

Lactiferous ducts—connect alveolar glands to

nipple

Female Mammary Glands

Figure 16.13a

Female Mammary Glands

Figure 16.13b

Mammography

X-ray examination that detects breast cancers too

small to feel

Recommended every 2 years for women between

40 and 49 years old and yearly thereafter

Mammograms

Figure 16.14

Stages of Pregnancy and Development

Fertilization

Embryonic development

Fetal development

Childbirth

Fertilization (VIDEO)

The oocyte is viable for 12 to 24 hours after

ovulation

Sperm are viable for 24 to 48 hours after

ejaculation

For fertilization to occur, sexual intercourse must

occur no more than 2 days before ovulation and

no later than 24 hours after

Sperm cells must make their way to the uterine

tube for fertilization to be possible

Mechanisms of Fertilization

When sperm reach the oocyte, enzymes break

down the follicle cells of the corona radiata

around the oocyte

Once a path is cleared, sperm undergo an

acrosomal reaction (acrosomal membranes break

down and enzymes digest holes in the oocyte

membrane)

Membrane receptors on an oocyte pull in the head

of the first sperm cell to make contact

Mechanisms of Fertilization

The membrane of the oocyte does not permit a

second sperm head to enter

The oocyte then undergoes its second meiotic

division to form the ovum and a polar body

Fertilization occurs when the genetic material of a

sperm combines with that of an oocyte to form a

zygote

The Zygote

First cell of a new individual

The result of the fusion of DNA from sperm and

The zygote begins rapid mitotic cell divisions

The zygote stage is in the uterine tube, moving

toward the uterus

Cleavage

Rapid series of mitotic divisions that begins with

the zygote and ends with the blastocyst

Zygote begins to divide 24 hours after fertilization

Three to 4 days after ovulation, the preembryo

reaches the uterus and floats freely for 2–3 days

Late blastocyst stage—embryo implants in

endometrium (day 7 after ovulation)

Figure 16.15

Cleavage

Fertilization

Secondary

oocyte

OvulationUterus

Endometrium

Uterine tube

Blastocyst

cavity

Inner cell

Trophoblast

Zygote

(fertilized

cleavage

4-cell stage

blastocyst

Late blastocyst

(implanting)

Morula

(a) (b) (d) (e)(c)

(a)(b)

Figure 16.15, step 1

Cleavage

Secondary

oocyte

OvulationUterus

Endometrium

Uterine tube

Cleavage

Fertilization

Secondary

oocyte

OvulationUterus

Endometrium

Uterine tube

Zygote

(fertilized

Cleavage

Fertilization

Secondary

oocyte

OvulationUterus

Endometrium

Uterine tube

Zygote

(fertilized

cleavage

4-cell stage

(a) (b)

(a)(b)

Cleavage

Fertilization

Secondary

oocyte

OvulationUterus

Endometrium

Uterine tube

Zygote

(fertilized

cleavage

4-cell stage

Morula

(a) (b) (c)

(a)(b)

Cleavage

Fertilization

Secondary

oocyte

OvulationUterus

Endometrium

Uterine tube

Blastocyst

cavity

Zygote

(fertilized

cleavage

4-cell stage

blastocyst

Morula

(a) (b) (d)(c)

(a)(b)

Cleavage

Fertilization

Secondary

oocyte

OvulationUterus

Endometrium

Uterine tube

Blastocyst

cavity

Inner cell

Trophoblast

Zygote

(fertilized

cleavage

4-cell stage

blastocyst

Late blastocyst

(implanting)

Morula

(a) (b) (d) (e)(c)

(a)(b)

Developmental Stages

Embryo—developmental stage until ninth week

Morula—16-cell stage

Blastocyst—about 100 cells

Fetus—beginning in ninth week of development

The Embryo

The embryo first undergoes division without

growth

The embryo enters the uterus at the

16-cell state (called a morula) about 3 days after

ovulation

The embryo floats free in the uterus temporarily

Uterine secretions are used for nourishment

The Blastocyst (Chorionic Vesicle)

Ball-like circle of cells

Begins at about the 100-cell stage

Secretes human chorionic gonadotropin (hCG) to

induce the corpus luteum to continue producing

hormones

Functional areas of the blastocyst

Trophoblast—large fluid-filled sphere

Inner cell mass—cluster of cells to one side

The Blastocyst (Chorionic Vesicle)

Primary germ layers are eventually formed

Ectoderm—outside layer

Mesoderm—middle layer

Endoderm—inside layer

The late blastocyst implants in the wall of the

uterus (by day 14)

Derivatives of Germ Layers

Ectoderm

Nervous system

Epidermis of the skin

Endoderm

Mucosae

Glands

Mesoderm

Everything else

Embryo of Approximately 18 Days

Figure 16.16

Development After Implantation

Chorionic villi (projections of the blastocyst)

develop

Cooperate with cells of the uterus to form the

placenta

Amnion—fluid-filled sac that surrounds the

embryo

Umbilical cord

Blood-vessel containing stalk of tissue

Attaches the embryo to the placenta

Embryo of Approximately 18 Days

Figure 16.16

The 7-week Embryo

Figure 16.17

Functions of the Placenta

Forms a barrier between mother and embryo

(blood is not exchanged)

Delivers nutrients and oxygen

Removes waste from embryonic blood

Becomes an endocrine organ (produces

hormones) and takes over for the corpus luteum

(by end of second month) by producing

Estrogen

Progesterone

Other hormones that maintain pregnancy

The Fetus (Beginning of the Ninth Week)

All organ systems are formed by the end of the

eighth week

Activities of the fetus are growth and organ

specialization

This is a stage of tremendous growth and change

in appearance

Photographs of a Developing Fetus

Figure 16.18a

Figure 16.18b

Photographs of a Developing Fetus

Table 16.1 (1 of 2)

Development of the Human Fetus

Table 16.1 (2 of 2)

Effects of Pregnancy on the Mother

Pregnancy—period from conception until birth

Anatomical changes

Enlargement of the uterus

Accentuated lumbar curvature (lordosis)

Relaxation of the pelvic ligaments and pubic

symphysis due to production of relaxin

Physiological changes

Gastrointestinal system

Morning sickness is common due to

elevated progesterone and estrogens

Heartburn is common because of organ

crowding by the fetus

Constipation is caused by declining

motility of the digestive tract

Physiological changes (continued)

Urinary system

Kidneys have additional burden and

produce more urine

The uterus compresses the bladder,

causing stress incontinence

Respiratory system

Nasal mucosa becomes congested and

swollen

Vital capacity and respiratory rate increase

Dyspnea (difficult breathing) occurs

during later stages of pregnancy

Cardiovascular system

Blood volume increases by 25–40%

Blood pressure and pulse increase

Varicose veins are common

Childbirth (Parturition)

Labor—the series of events that expel the infant

from the uterus

Rhythmic, expulsive contractions

Operates by the positive feedback mechanism

False labor—Braxton Hicks contractions are

weak, irregular uterine contractions

Childbirth (Parturition)

Initiation of labor

Estrogen levels rise

Uterine contractions begin

The placenta releases prostaglandins

Oxytocin is released by the pituitary

Combination of these hormones oxytocin and

prostaglandins produces contractions

Figure 16.19

Initiation of Labor

Hypothalamus sends efferent

impulses to posterior pituitary,

where oxytocin is stored

Posterior pituitary releases

oxytocin to blood; oxytocin

targets mother’s uterine

muscle

Uterus responds

by contracting

more vigorously

Afferent

impulses to

hypothalamus

Pressoreceptors

in cervix of

uterus excited

Baby moves

deeper into

mother’s birth

Positive feedback

mechanism continues

to cycle until interrupted

by birth of baby

Initiation of Labor

Baby moves

deeper into

mother’s birth

Initiation of Labor

Pressoreceptors

in cervix of

uterus excited

Baby moves

deeper into

mother’s birth

Initiation of Labor

Afferent

impulses to

hypothalamus

Pressoreceptors

in cervix of

uterus excited

Baby moves

deeper into

mother’s birth

Initiation of Labor

Afferent

impulses to

hypothalamus

Pressoreceptors

in cervix of

uterus excited

Baby moves

deeper into

mother’s birth

Initiation of Labor

muscle

Afferent

impulses to

hypothalamus

Pressoreceptors

in cervix of

uterus excited

Baby moves

deeper into

mother’s birth

Initiation of Labor

muscle

Uterus responds

by contracting

more vigorously

Afferent

impulses to

hypothalamus

Pressoreceptors

in cervix of

uterus excited

Baby moves

deeper into

mother’s birth

Positive feedback

mechanism continues

to cycle until interrupted

by birth of baby

Stages of Labor

Dilation

Cervix becomes dilated

Full dilation is 10 cm

Uterine contractions begin and increase

Cervix softens and effaces (thins)

The amnion ruptures (“breaking the water”)

Longest stage at 6–12 hours

Figure 16.20 (1 of 3)

Stages of Labor

Expulsion

Infant passes through the cervix and vagina

Can last as long as 2 hours, but typically is 50

minutes in the first birth and 20 minutes in

subsequent births

Normal delivery is head first (vertex position)

Breech presentation is buttocks-first

Stages of Labor

Figure 16.20 (2 of 3)

Stages of Labor

Placental stage

Delivery of the placenta

Usually accomplished within 15 minutes after

birth of infant

Afterbirth—placenta and attached fetal

membranes

All placental fragments should be removed to

avoid postpartum bleeding

Stages of Labor

Figure 16.20 (3 of 3)

Developmental Aspects of

the Reproductive System

Gender is determined at fertilization

Males have XY sex chromosomes

Females have XX sex chromosomes

Gonads do not begin to form until the eighth week

Testosterone determines whether male or female

structures will form

Reproductive system organs do not function until

puberty

Puberty usually begins between ages 10 and 15

Enlargement of testes and scrotum signals

onset of puberty (often around age 13)

Females

Budding breasts signal puberty (often around

age 11)

Menarche—first menstrual period

Menopause—a whole year has passed without

menstruation

Ovaries stop functioning as endocrine organs

Childbearing ability ends

There is a no equivalent of menopause in males,

but there is a steady decline in testosterone

A Closer Look: Contraception

Contraception—birth control

Birth control pill—most-used contraceptive

Relatively constant supply of ovarian

hormones from pill is similar to pregnancy

Ovarian follicles do not mature, ovulation

ceases, menstrual flow is reduced

Morning-after pill (MAP)

Taken within 3 days of unprotected

intercourse

Disrupts normal hormonal signals to the point

that fertilization is prevented

Other hormonal birth control devices cause

cervical mucus to thicken

Minepill (tablet)

Norplant (rods placed under the skin)

Intrauterine device (IUD)

Plastic or metal device inserted into uterus

Prevents implantation of fertilized egg

Sterilization

Tubal ligation (females)—cut or cauterize

uterine tubes

Vasectomy (males)—cut or cauterize the

ductus deferens

Coitus interruptus—withdrawal of penis prior to

ejaculation

Rhythm (fertility awareness)—avoid intercourse

during period of ovulation or fertility

Record daily basal temperature (body

temperature rises after ovulation)

Record changes in pattern of salivary mucus

Barrier methods

Diaphragms

Cervical caps

Condoms

Spermicidal foams

Sponges

Abortion—termination of pregnancy

Miscarriage—spontaneous abortion is common

and frequently occurs before a woman knows she

is pregnant

RU486 or “abortion pill”—induces miscarriage

during first 7 weeks of pregnancy

Flow Chart of Events that

Must Occur to Produce a Baby

Figure 16.21 (1 of 2)

Some Contraceptive Devices

Figure 16.21 (2 of 2)

uterine (menstrual) cyclepchs.psd202.org/documents/dpohlman/1519742914.pdf · uterine (menstrual)...

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